Molecular identification of some Hoplolaimus species from the USA based on duplex PCR, multiplex PCR and PCR-RFLP analysis

Two different molecular approaches, a multiplex PCR and PCR-RFLP of ITS-rDNA, were developed for the identification of Hoplolaimus species. DNA sequences of H. columbus, H. galeatus, H. concaudajuvencus, H. magnistylus, H. seinhorsti and three undescribed Hoplolaimus species were used to design species-specific primers. Three reverse species-specific PCR primers for H. columbus, H. galeatus and H. magnistylus were developed using the ITS1 region exhibiting interspecific variation. Three species-specific PCR primers in combination with the forward primer, Hoc-1f, produced distinct amplicons of 580 bp for H. columbus, 120 bp for H. galeatus and 340 bp for H. magnistylus. We successfully identified each of three species by multiplex PCR when all three were mixed in a single PCR reaction. Restriction enzyme digests of the PCR amplicon using HaeIII and RsaI permitted discrimination of H. columbus, H. galeatus, H. magnistylus, H. concaudajuvencus, H. sp. 1, H. sp. 2 and H. sp. 3 from each other. These results suggest that these molecular techniques allow for rapid, easy and reliable identification of Hoplolaimus species.